Sam and Richelle Arber spoke of their worry for missing son Paul at a press conference in Hamilton.

MISSING: Australian Tennis Coach, Paul Arber.

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Police hold grave fears for the safety of a well-known Australian tennis coach who is missing in Hamilton.

Melbourne tennis identity Paul Arber - a former Kooyong Tennis Club captain and the 2012 Victorian Jewish Tennis Champion - was last seen near Steele Park about 9pm on Saturday.

Arber was in Hamilton with eight of his charges for a junior tennis tournament hosted by Tennis Waikato-Bays.

The tournament was held at courts near where Arber was last seen.

Police were sighted searching the nearby Waikato River about 5pm yesterday but authorities did not disclose whether they had found anything relating to Arber's disappearance.

Desperate for clues to Arber's whereabouts, they have set up a mobile police van in Grey St, near Steele Park, the last known sighting of the tennis champ.

A dummy was placed on the roadside dressed in a grey tracksuit top with a tennis logo, the same type Arber was wearing when he went missing.

His wallet and keys were later found about 400 metres down Cook St.

Immediately before his last sighting Arber was seen to stop and pat the dog of a couple who were out walking their pet, Detective Inspector Karl Thornton CIB said.

That couple was urged to make contact with police, Thorton said.

"We are becoming increasingly concerned that we have not heard from Mr Arber," he said.

"He is not familiar with the area and does not know anyone in Hamilton."

Arber's family flew to New Zealand at the weekend to assist with the search for the tennis player.

The news of Arber's disappearance has quickly spread through the Melbourne tennis community and a Facebook page had been set up to share information between family and friends as the situation unfolded.

Kanga Tennis Tours international director Mark Sheppard said four coaches searched the streets of Hamilton when Arber failed to return to the mini bus.

The frantic quartet waited until about 11pm before they reported him missing to police.

''Obviously it's 12 hours before they take these things seriously but we knew there was a problem so we're just really concerned,'' Sheppard said.

''We just hope he comes back, but we just can't be sure.''

An emotional Sheppard, who has known Arber for about seven years, said his disappearance was out of character.

''We just had this huge concern because he's normally a really reliable guy,'' he said.

''There's no way he'd ever leave his eight kids unattended at the bus.

''If anyone knows where he is, just let us know. Just let him come back to us. We just want him back with us.''